Thirty Days
by S.N.Sterling
Summary: A look into the sex lives of Rivaille and Eren for thirty days. Otherwise known as the 30 Day OTP Challenge (NSFW Version). Riren/RivaEre/Top!Rivaille and Bottom!Eren
1. Day One: Masturbation

**Chapter Summary: Rivaille had been gone for weeks on another business trip to France, and Eren was left to take care of his sexual desires alone for the hundredth time.**

* * *

Eren's skin felt hot, burning with the fever of pure pleasure running through his veins as he pressed the palm of his hand against the firm bulge in his jeans, biting down on the fingers of his free hand almost painfully. His voice came out as a whine, muffled by his fingers as he ground his hips up against his own hand, his body already scorching with white-hot desire. His cheeks were flushed as his palm worked against the clothed erection between his legs, and he could _feel_ himself getting harder as his mind wandered helplessly.

His fingers pressed and rubbed against the bulge of his pants while he imagined his hand as Rivaille's, and he squeezed his eyes shut and turned his head to the side against his pillow while he envisioned Rivaille lustily watching him from above. He could almost hear the man's teasing voice in the back of his mind; could almost _feel _the puffs of warm breath against his ear and the tingle of gentle lips caressing his skin as Rivaille spoke.

He shoved his hips against his palm desperately while he imagined the way Rivaille would whisper in his ear – little teasing taunts of, _"Does it feel good, Eren?"_ and, _"Moan for me. I want to hear you."_ He groaned audibly as the man's voice repeated itself in his mind, and he tried to control his panting as he bit on his fingers, another whine escaping him as the hand between his legs hurriedly unzipped his jeans.

"N-nngh…I want to be touched by you," Eren moaned, desperate for the contact of his own hand as long as he was imagining it to be Rivaille's. He gasped heatedly once he reached into his pants and took hold of his erection, wiggling enough to lower his jeans so could kick them off and pull his cock free. His hips arched against the heated touch, and he bit down on the fingers in his mouth to muffle the shameless moan that threatened to escape his lips.

His mind wandered to the depths of his sexual fantasies while he imagined that it was Rivaille stroking his cock and running his thumb along the prominent veins before nudging against the slit in a way that made Eren's back arch in pleasure. His fingers worked over the shaft almost frantically, squeezing and tugging on his hard length while the fingers caught between his teeth finally moved down to cup his balls, his legs spreading wider and his back arching higher automatically.

"A-ah, nngh…_Rivaille_," the brunet moaned, voice cracking slightly as he thrust his hips up against his hand, his pelvis gyrating and his toes curling as slick fingers squeezed and stroked his balls in a way that made his mind dizzy with pleasure. His chest heaved and his head pressed back against soft pillows while he pleasured himself, groaning in anticipation as his fingers trailed down to his perineum, pressing and rubbing against the sensitive area teasingly.

A halfhearted whine managed to break past his lips when his fingers moved farther to stroke over the tight muscle of his entrance, and Eren bit his lower lip as he imagined Rivaille's fingers pressing against the tight ring _almost_ firmly enough to push inside. "_Please_," he whispered, rubbing his fingers against his entrance while he continued to stroke his cock, occasionally thumbing the slit and spreading pre-cum down along his shaft.

His hips continued to jerk and roll against his hand as he shift to spread his legs open a little more, chest heaving and breath coming out in short pants as he eased a finger inside of himself, doing his best to ignore the slight discomfort of being penetrated. His voice broke into a muffled gasp as he bit down on his lower lip, using the slight pain as a distraction while he slid his finger deeper, thrusting the digit forward until it was knuckle deep. His head soon fell to the side while he tried to catch his breath, giving his body a moment to relax and adjust to the intrusion and giving his cock simple, languid strokes that drew quiet groans from the back of his throat.

"Hhnn…nngh, _Rivaille_…stretch me, open me up—I want to _feel_ you," Eren moaned, imagining the way Rivaille would chuckle huskily by his ear and pull his finger back out before thrusting it back in with a second digit and making the brunet writhe as he got to work spreading his fingers deep inside his body. He could feel the pleasurable sting of being stretched while he worked two fingers inside himself, groaning and grinding down to get his fingers as deep as possible, and it wasn't long before he added a third to increase his pleasure.

His hips jerked and twitched, and he stroked along his inner walls while moans and gasps spilled from his lips, visualizing the way Rivaille should be bridged over him, kissing and biting at his neck with enough force to leave marks for a _week_. He curled his fingers inside himself, longing to press them deeper but finding it difficult in his position and settling for gripping his cock instead to tug and squeeze, sending moans spilling from his lips as he felt himself approaching climax.

His body burned with pleasure and desire, and his breathing picked up as he gasped and groaned, thrusting his fingers as deep as he could and stroking himself almost frantically as the pit in his stomach grew hotter with each pass of his thumb over the slit of his erection. His toes curled and his back arched as he shoved his fingers deep inside his body, whining Rivaille's name and begging for his release.

"Please, _please_—! Make me come, Rivaille, oh god, _please_, I'm so—nngh, so _close_—" Eren gasped, voice breaking as he curled his fingers and just barely brushed his prostate, his thumb pressing against the head of his cock and his hand squeezing the shaft hard enough to finally send him over the edge with a cry of Rivaille's name. His body tensed, his toes curled, and he came _hard_ in his hand, riding out his orgasm as a gasping, panting mess.

He fell back against the bed once the tension in his body eased, and Eren groaned as he slid his fingers back out, his stomach and lower body a complete disaster. His mind was blank with the afterglow of his orgasm, and his eyes slowly cracked open to stare at the camera positioned on the dresser across the room in a distant haze. The smell of sex and sweat lingered around him, and Eren groaned in well-earned exhaustion as his head sank back against the pillow beneath it, deciding to turn off the video camera later rather than now.

He imagined the way Rivaille would lean over to kiss his forehead and praise him for doing so well, and a slight smile made its way to his lips while he turned his head as if to lean into the gentle touch. Too tired to do much else after wearing himself out, Eren simply relaxed against the soft mattress of his and Rivaille's bed, breathing in the scent of his lover that lingered on the pillow beside his.

It hadn't been sex with Rivaille like he'd been craving for weeks, but it had been good enough for now, and Eren only hoped that Rivaille would fully satiate his cravings once he returned home in a few days and saw the recording Eren had made for him.


	2. Day Two: Impatience

**Chapter Summary: Rivaille's patience only lasts so long - and when he's been waiting all night to have his way with Eren, his patience depletes even faster. Who needs to take their clothes off for sex anyways?**

**Note: Almost all oneshots/chapters are independent of each other.**

* * *

"S-shit! Wait a minute would you—_nngh_, _Rivaille_!" Panting heavily and grasping at the broad shoulders of the man bridged above him, Eren couldn't help the desperate cry that left his lips as Rivaille's hips thrust roughly against his own. His fingers clutched at the dark fabric of Rivaille's suit jacket while skilled hands slid along his sides, and his body twitched helplessly beneath the gentle touches. His hips jerked up against his will, his clothed erection grinding against Rivaille's, and another breathy moan ripped itself from his throat.

"I've been waiting all night, Eren," Rivaille groaned by the brunet's ear, his hips rolling and pressing against Eren's in a way that made his skin burn with arousal. Trembling fingers scratched and gripped at his shoulders in response, and the quiet gasps and moans falling from Eren's lips went straight to Rivaille's groin.

"We're not—we're not even _home_ yet! I don't want to get your—_ah_! Stop that!" Eren ground out, gasping in painful pleasure once Rivaille bit down on the flushed skin of his neck. He tried to wiggle out from beneath Rivaille but to no avail, his body remaining trapped between the car seats and Rivaille's hips. One hand moving to brace against the door by his head, Eren let a harsh grunt slip out between his stifled moans, his hips defying the orders of his mind as they pressed up against Rivaille's firmly.

"You say that but I don't think you actually care," the shorter man teased, already aware that Eren's only worry would be getting the car dirty. Rivaille had to admit that the last time they'd decided to fool around in the backseat, he _had _scolded Eren for making a mess of the leather seats, but he had a plan this time. As long as they didn't get naked, everything would be fine.

"I do care!" Eren protested, lifting his head slightly and about to add more before his words slurred into another pleasured moan as Rivaille grasped his hips and thrust against him like he meant it. Shocks of pleasure shot through his veins with each press of Rivaille's hips against his, and Eren shuddered beneath the shorter man, his breath coming out in short gasps.

"We won't make a mess," Rivaille promised after a long moment, a groan falling from his own lips as he rocked against the brunet, his forehead slick with a thin layer of sweat and pressing against the seat above Eren's shoulder. His cock was painfully hard and trapped within the formfitting fabric of his slacks, and the friction between his and Eren's hips was nearly driving him delirious. He wanted nothing more than to get Eren on his knees and fuck him right then and there, but Rivaille knew better than to let his impulses get ahead of his right mind.

Protests dying quickly as his pants seemed to get tighter and tighter, Eren groaned as Rivaille moved against him. His right hand remained positioned firmly on the man's shoulder, fingers gripping the fabric of his jacket tightly. It was almost ridiculous how easy it was for Rivaille to turn him into a mess without even getting him naked first, and Eren had half a mind to frown at the thought before it was completely erased from his mind with a particularly rough thrust of Rivaille's hips. "F-fuck! God, _Rivaille_—do that again," he moaned, body arching against the shorter man's desperately.

His fingers found Rivaille's hair and threaded through the dark strands almost painfully, and a sharp nip was directed against his jaw. Gasping quietly as Rivaille scraped his teeth along his jawbone, Eren tugged on the man's hair before pulling him into a deep kiss as Rivaille finally repeated his earlier action, his hips firmly grinding down against Eren's. It wasn't more than a second before Rivaille's tongue was plunging into the brunet's mouth, and Eren groaned against the man's lips as their erections rubbed against one another through their clothes.

The kiss turned sloppy and rushed in record time, and Rivaille ran his tongue along the saliva that threatened to spill down Eren's chin before crushing their lips together once again, his hands grasping the taller male's hips as they pressed against each other. Their skin was flushed beneath the clothes they still wore, and Rivaille moved back for a short moment to sit up, his hands pulling and pushing against Eren's hips to turn him over.

Getting the hint almost immediately, Eren bit at his lower lip in slight hesitation before doing as Rivaille wanted by rolling onto his stomach and pulling his knees up with his forearms braced against the seat beneath him. Curiously, green eyes glanced behind himself to watch as Rivaille tugged his hips closer and sat up on his right knee while his left foot was firmly planted against the floorboards.

"Are we—?" Unable to finish his question before Rivaille's hips were against his ass, Eren gasped and gripped at the expensive leather beneath his fingers. His body jerked forward as Rivaille thrust against his ass, his clothed erection rubbing against the seam of Eren's jeans, and Eren couldn't help the moan of Rivaille's name that escaped his lips.

"_Shit—!_ Even with your pants on, you still feel _amazing, Eren_," Rivaille groaned, one hand traveling down to press between Eren's legs, cupping his erection and squeezing in a way that made Eren shudder and gasp with keen anticipation. Eren's hips rocked down against his hand while he thrust against the brunet's ass, and Rivaille almost swore that the heat was beginning to get to his head when Eren spread his legs as far as he could with the limited space of the backseat.

"_Nngh, Rivaille…harder_—I can't feel you properly," Eren murmured breathlessly, his chest heaving against the seat beneath him while Rivaille's hand stroked and squeezed between his legs. His nails dug into his palms when Rivaille suddenly shoved his hips forward with more force, rocking Eren's body forward and drawing loud moans from both of their lips.

"What about now? Can you feel me _now, Eren_? Can you feel my cock pressing against your ass? Are you imagining me inside you, driving into you without your clothes in the way?" Rivaille teased, his voice husky and sultry as he thrust his hips against Eren's ass harder, grinding against him and firmly palming the brunet through his jeans. His only response was an incoherent moan of agreement from Eren and the furious nodding of the brunet beneath him, and Rivaille took that as a sign to continue just as he was.

Grunts and groans filling the hot air between them, Rivaille drove his hips against Eren while the brunet ground back against him and tried to shake the hair from his eyes uselessly. The burning pit in his stomach began to grow more intense with alarming speed, and Rivaille wasn't far behind at all as his hips worked against Eren's ass almost harshly.

Skin burning beneath their clothes and voices cracking with pleasured moans and short cries of each other's names, Eren was the first to come as Rivaille thrust against him one last time, the shorter man following only half a second later. Throats dry and bodies borderline exhausted, Eren let himself slump against the seat beneath him while Rivaille forced himself to sit up, panting quietly under his breath and running the back of his hand against his forehead.

"Well that was fun," Rivaille mused, finally moving to shrug off his suit jacket and trying not to mind the feeling of his soiled underwear rubbing against him. He shifted his legs just slightly while Eren groaned at his comment and finally shook the hair from his eyes so he could glance back towards Rivaille.

"But doing laundry won't be," he pointed out, still pleasantly surprised by the warm tingly feeling of his orgasm passing through his veins and prickling his skin. He hummed quietly under his breath when Rivaille shot him a displeased look, and a slight yawn fell from his lips as he sat up to peck the man's lips gently. "Just pray that none of it gets on your pants enough to be noticeable on the way home," Eren mentioned, smirking playfully at the unpleasant frown that crossed Rivaille's lips.

"I'll just have Erwin pay for dry-cleaning. He's the one who fucking made dinner run into overtime anyways," Rivaille grumbled, slightly taken aback when Eren pressed another quick kiss to his lips and pulled back before Rivaille could kiss him back. He almost wanted to ask what the brunet was smirking at, but his question was soon answered as Eren hummed thoughtfully under his breath.

"I dunno. Maybe we should make sure that dinner _always _runs into overtime now."

And Rivaille could've sworn the wink Eren sent him was an invitation for more once they got home.


End file.
